Function rect_iter::gen_rect

pub fn gen_rect<D, T, I, J>(
    source: &impl Get2D<Item = T>, 
    gen_dist: impl Fn() -> D, 
    source_range: RectRange<I>, 
    dest_range: RectRange<J>
) -> Result<D, IndexError> where
    D: GetMut2D<Item = T> + Default,
    T: Clone,
    I: Num + PartialOrd + ToPrimitive + Copy,
    J: Num + PartialOrd + ToPrimitive + Copy,